Diarrhea, characterized by the frequent defecation of liquid or liquid-like stools, often develops as a side effect during clinical treatment with chemotherapeutic agents. This adverse effect is most commonly associated with chemotherapeutic agents such as 5-fluorouracil, cisplatin or irinotecan hydrochloride. In particular, late diarrhea due to the administration of irinotecan can be prolonged, may lead to dehydration and electrolyte imbalance and can be, in some cases, sufficiently serious that irinotecan administration must be modified, interrupted or discontinued. Diarrhea poses a problematic symptom for patients, and because it may provoke reductions in irinotecan doses or the frequency of irinotecan administration, diarrhea may compromise the therapeutic efficacy of irinotecan.
While there is a substantial need for development of an agent for preventing diarrhea, particularly late diarrhea caused by irinotecan, no definite and efficacious method for preventing irinotecan-induced diarrhea has been identified. It is therefore an object of the present invention to provide an agent for preventing diarrhea, in particular late diarrhea, induced by irinotecan administration.